Tag: rodents

What’s the News: Scientists have reversed Parkinson’s disease-like brain damage and motor problems in mice and rats using neurons grown from human embryonic stem cells. The new technique, described online in Nature earlier this week, brings scientists closer to similar treatments for people with Parkinson’s.

What’s the News: In the animal kingdom, prey species must follow one rule above all others: keep away from predators. To do this, some animals take chemical cues from the urine they stumble upon. Now, new research published in the Proceedings of the National Academy of Science has identified a single molecule in the urine of many mammalian carnivores that causes rodents to scurry in fear. This chemical could eventually help scientists understand instinctual behavior in animals.

In the rigid social universe of Revenge of the Nerds-style 1980s movies, jocks beget jocks beget jocks, and the bespectacled geeks they push around beget generations of the same. But could being a victim of social bullying actually be inherited? A new study of DISCOVER’s favorite rodent, the marmot, shows that at least in the animal kingdom, the answer can be yes.

Daniel Blumstein and colleagues tracked yellow-bellied marmots that make their home in the Colorado Rockies for a five year period, from 2003 to 2008. For their study out in the Proceedings of the National Academy of Sciences, the team tracked the family relationships of the individual marmots, as well as who antagonized whom.

Marmots don’t have Facebook yet, but animals living among clusters of burrows in Colorado do interact enough for observers to plot networks with each marmot as a node. An exchange might be friendly, such as a marmot grooming a neighbor or settling down tranquilly nearby. Or a social interaction might go sour, with one marmot nipping or chasing another. “Marmots are grumpy with each other,” Blumstein says, but rarely cause serious injuries. [Science News]

Yellow-bellied marmots are taking to global warming just fine—so far. A Naturestudy of the hibernating Rocky Mountain-dwellers found that over the last 30-plus years, the marmots have grown both in girth and in population, and the researchers think they know why.

Study author Arpat Ozgul says that the marmots have limited time to accomplish the things on their summertime agenda—namely, eating, mating, and giving birth before they crawl back into their seven- to eight-month hibernation.

But as the Colorado summers have grown longer, so too has the time the marmots have to do all of these things—and do them better. This extra preparation (and reproduction) time means that “they are more likely to succeed and survive,” said Ozgul [Scientific American].

Because of the extra time, marmots studied grew in average weight from approximately 6.8 pounds to 7.5. And since 2001 the marmot population has exploded, adding an average of 14 individuals each year; in the previous 25 years the population growth rate was only .56 per year.

The naked mole rat is a species with a long list of peculiarities. The mole rat is about the same size as the more hirsute wild mouse, but lives seven times as long, sometimes reaching the ripe old age of 28. The creatures almost never poke their noses beyond the snug confines of their burrows and tunnels, and instead live out their lives underground in the dark. They’re also the only mammals who have a social structure that resembles an ants’ nest or beehive, where only one dominant female mates and reproduces.

Finally–and this is the part that most interests researchers–naked mole rats never get cancer.

A new study in the Proceedings of the National Academy of Sciences probed the mole rats’ robust good health, and determined how they beat cancer. The naked mole rat’s cells hate to be crowded, it turns out, so they stop growing before they can form tumors…. Normal human and mouse cells will grow and divide in a petri dish until they mash tightly against one another in a single, dense layer–a mechanism known as “contact inhibition.” Naked mole rat cells are even more sensitive to their neighbors, the researchers found. The cells stop growing as soon as they touch [ScienceNOW Daily News]. Researchers hope that the mechanism can one day lead to novel treatments for cancer, where cancerous cells won’t stop multiplying and form tumors.

Warmer winters in Norway seem to be causing a decline in lemming populations, according to a new study, and researchers say the decline of the rodent is having a cascading effect. Lemming predators, like foxes and owls, have been forced to hunt different prey in what researchers call a clear-cut example of how global warming can have a disruptive impact on entire ecosystems.

Lemming populations throughout Scandinavia tend to explode naturally every three to five years, causing huge numbers to go in search of food. Occasionally this leads the rodents to jump into water and swim to new pastures new—the origin of the myth that lemmings commit mass suicide. When lemmings boom, they’re hard to miss. Norwegians have had to use snowplows to clear the squashed rodents off the roads [National Geographic News]. But the study of lemming populations during the last four decades found no population explosions since 1994.

A new study of the prairie vole, a rodent species famed for its monogamous ways, has shown that the vole’s brain chemistry changes when its mate is taken away, and that it loses some of its vim and vigor. Researchers compared the behavior of males who were separated from either their mates or their siblings, and found that those voles who had lost their loyal mates were passive and unresponsive–maybe even depressed.

Prairie voles are one of the few mammals that are generally monogamous; the mates form life-long bonds and rear their pups together. In the new study, researchers subjected all the male voles to stress tests, like dunking them in basins of water and holding them suspended by their tails, and found that the voles whose mates had been spirited away put up less struggle. In the water, for example, they floated listlessly instead of paddling for their lives. These voles “basically were passive — they gave up,” [study coauthor Larry] Young said. “I would be hesitant to say that these animals were depressed, but their behavior is reminiscent of what you would see in a depressed person” [HealthDay News].

The trick to keeping organs working well into old age might be taking out the trash, according to a study in Nature Medicine [subscription required]. Researchers led by Ana Maria Cuervo of Yeshiva University in New York have slowed the aging process in the livers of mice by tinkering with a system that recycles the damaged proteins hanging around in a cell.

Molecules responsible for “chaperone-mediated autophagy“ handle about 30 percent of the cells’ damaged proteins, escorting them to inner cell structures called lysosomes, where enzymes break the proteins down. Studies by Cuervo have shown that the disposal system becomes less efficient as cells grow older. They’ve also pinpointed the reason for the age-related decline — a loss of receptors on the surface of the lysosomes that causes a buildup of damaged proteins in the cell [U.S. News & World Report].